Twin type gear pump



April 15, 19:41. h F, EGERsDRFER 2,238.313 v 'rwm 'rYrsaan PUIP Filed kann 4. 1959 3 sheets-sheet 1 MyW/1 F. EGERsDRr-'ER TWIN TYPE GEAR Pun? Filed march 4. 1939 April l5, 19412..

3 sheets-sheet 2 April 15, 1941. F. EGERSDRFER 2,238,313

'nmz TYPE-Gsm Pmi? Filed larh 4. 195s s sheets-sheet y the gear wheels.

Patented Apr. l5, 19441/ UNITED STATES PATENT Aoli-FICE .2,238,313 TWIN TYPE GEAR PUMP Fritz Egersdrfer, Berlin, Germany Application March 4, 1939, Serial No. 259,884v

In Germany March 4, 1938 15 Claims.

are not deformed and jamming of the gear wheels within the said chambers is avoided. Another object of the improvements is to provide a gear pump which can be manufactured at low cos-t. With these and other objects in view my invention consists in providing the chambers or bores enclosing the impelling gear wheels in an integral body, and placing the suction and delivery passages in one of the heads of the gear pump, so that the suction and delivery pipes are fixed to the said head. \Further, the said suction and delivery passages are connected respectively with suction and delivery chambers communicating with the chambers enclosing the gear wheels through ducts made in the said body, and, preferably, thesaid du'cts and other ducts made in the said body are in the form of bores having circular cross-sections and disposed with their axes parallel to the axes of the chambers enclosing Therefore, all the said bores can be manufactured on the drilling machine tion. 'Thereby accurate work is insured, and' the cost of the manufacture is small.

. .The character of the invention, however, will be best understood by reference to one of its structural forms as described in the following specification and illustrated in the accompanying drawings in which:

Fig. l is a cross sectional view o'n line I-I of Fig. 2, showing a gear pump having the invention applied thereto: Y

Fig2 is an axial section on line 2-2 of Fig. '1;

Fig. 3 is a longitudinal 'section on line 3-3 of Fig. 1;.

Fig. 4 is a longitudinal section` on line 4-4 of Fig. l;

Fig. 5 is a longitudinal section on line 5-5 of Fig. 1;

Fig. 6 is an end view ofthe cover side of the pump and Fig. i is a cross sectional View on line if? of Fig. 2.

Sar reference numerals denote similar parts in the arent views.

tion 3 of the cover II, with-an interposed sleeve with the body fixedon the table in the same posiv casing I and the front cover I3.

Referring now to the drawings in greater detail, the pump casing is formed by a cylindrical body I having three parallel axially directed bores 2, 3 and 4 for reception of three intermeshing pinions 5, 6 and 'I forming two pairs of interlmeshing fluid-displacing spur gears. `Sleeves 8,

9 vand I0 form .the packing means at' the rear faces of the pinions; the sleeves 8 and I Ilare in the form rof separate members inserted in the casing while the sleeve 9 may be formed by a hub portion or projection of the rear cover II. On their opposite end faces, the pinions lie liquid tight against a plate I2 interposedbetween the The central pinion' is keyed on' an operating shaft I4 in a floating condition, permitting endwise relative movement, by 'a key member I5 or the like, while the pinions 5 and I are rotatably mounted on tubular members 60 and 6I fixed within the sleeves I0 and 8, respectively. 'I'he operating shaft I4 issupported in the hub poror bushing I6 and is resiliently coupled to the motor shaft I8 at Il. A collar I9 on the shaft is sandwiched between packing washers 20, under action of. a spring 2| hollow shaft I4 and in the pinions 5, 6 and 'I admit access of the fluid which is to be moved to all surfaces exposed to friction, thereby ensur-v ing effective lubricating action by said fiuid.

Further axially directed bores in the casing form passage channels or Aducts for thefluid on the suctionand pressure side, and receive control devices and valves, as will be described below; cross channels in the two covers, i. e.,'out side the casing serve to interconnect the said various bores.

, The two suction chambers 23 and 24 of the twin pump communicate with bores 25 and 26 while the pressure chambers 21 and 28 thereof communicate with bores 23'and 30. The bores 25 and 26 communicate with chambers 62 and 63 made in the head I3 and ending in threaded bores 64 and 65 adapted to have suction pipes secured thereto. y

3| of th casing adjacent to the cover II the bores 25and 26 are normally closed on, the side 3I-of the casing adjacent to the cover II, by

valves 32 and 33. VThe valves are guided in the bores, but their springs 34 are disposed in chan` nels e5 e in the cover il. Thusin operative condition of the pump the valves 32, 33 close the suction side agaiii 1st' the saidchannels 35.

which through the bores 2@ and communicate with the pressure chlcers it andZt; it is there= Radial bores 22 in the 'at their opposite ends and at the sidev by possible to feed fuel directly to the carburettor of the engine in orderto illl up the same prior to the starting of the engine, through the bypass thus formed as the pressure exerted, for example, by a hand pump, is sumcient to overcome the adjusted compression of the valve springs. i Check valves 36 shut the bores 29 and 36 on the side adjacent to the cover I3 and plate I2 in the inoperative condition of the pump and when the'fuel supply is interrupted on either side. The heads of the valves 36 are guided in sleeves 38 which are-mounted in the plate I2 and project into the bores 26 and 36 of the casing I, thus centering the plate I2 and its bores relatively to the body I and its bores, while the valves proper with their springs 39 are received in a channel 66 made in the cover I3. A threaded bore 46 (Fig. 4) is provided to. permit connection of vthe channel 66 to a control pressure gauge (not shown). The channel 66 communicates With a central duct 4I in the cover I3 adapted forconnection with the pressure pipe to the Carburettor. It will be noted that in Figs. 4 and 5 the same bore 30 and its valve 36 and spring 39have been illustrated. But it will be understood that the bore 29 is provided with a similar valve 36 and spring 39 which are likewise located in the recess 66 communicating with the threaded bore 4I, as is shown in Fig. 6.

Seated in two further axially directed bores 43 and 44 in the casing I, between the bores 25 and or 26 and 29,. respectively, are guiding sleeves 45 for control pistons 46. On the side adjacent to the cover-II the bores 43 and 44 terminate each in oneof the channels, communicating with the bores 29, 30 and the pressure chambers 21, 28 of the pairs of gears. By reason of this, the pistons acted upon by pressure springs 41 are adjusted in accordance with the pressure of the uid within the pressure passages. On the side adjacent to the cover I3 the bores 43, 44 terminate in chambers 46 made in the head I3 which through ducts 66 made in plugs 49 communicate with ducts 69 adapted for connection with the pressure pipe of the compressor of the engine (not shown). In case of Vengines without supercharging, the chambers 48 communicate directly with the atmosphere. By connecting the chambers 48 with the pressure pipe of the compressor of the engine by two ducts 69 and pipes connected thereto the safety of the system is increased. The plugs 46 are provided with set screws 66 adapted to adjust the tension of the springs 41. At a predetermined pressure within the pressure pipe of the compressor of the engine and within the passages 48 theA pistons 46 are lifted by such an amount that a by-pass channel is exposed for establishing communication between the suction and pressure sides. Tothis end, the bores 43.

44 are -formed with annular recesses 6I communicating with bores 26, 26 on the suction side, in the manner indicated in Fig. 1 in dotted lines. Inclinedslots 62 provided in the guiding sleeves 46 adjacent to the recesses 6I cause a larger or vsmaller cross section to be exposed by the pistons depending on their adjustment. Advantageously, the pistons are provided tocarry out a rotating motion together with their axial movement and to this end, a pin 64 may project y pressor for supplying e 664 may into a helical grooveor slot 63 in'each of the pistons.

The operation of the V:pump is as follows: Y It may be assumed that the pump is used for supplying fuel to an engine provided with a comair under pressure. Before the engine is started fuel is supplied to the suction side of the fuel pump throughrthe bores 64, 66 and the bores 25 and 26 bygm/eans of a hand-operated pump. By the pressure built up within the said bores the valves 32 and 33 are unseated, and the fuel flows through the channels 36, the bores 29 and 30, the channel 66 and the bore 4I to the carburettor. Now the engine is started, and the fuel pump connected therewith begins its operation. The fuel is admitted through the bores 64, and 25, 26 to the suction chambers 23, 24, and it is conveyed by the gear wheels 6, 6 and 1 to the bores 29, 30, the channel 66, and the bore 4I to the fuel pipe or pipes connected with the engine. While the fuel thus flows from the bores 29, 30 into the channel 62 it opens the valves 36, 36. The pressure within the said channel may be ascertained by the pressure gauge connected to the bore 40.

The pistons 46 are controlled by the iiuid pressure within the channels 35, 35, by the fluid pressure transmitted to the chambers 48 from the pressure pipe of the air compressor of the engine and by the pressure of the springs 41, and they are held in equilibrium and in a position so that there is ordinarily communication through the slots 52 between lthe bores 25, 26, the channels 36 and the bores 29, 30, so that any excess of fuel supplied by the pump is returned from the channels 35 and through the annular recesses 5I to the bores 25 and 26. Thus constant pressure is maintained at the pressure side of the pump, the said pressure dcpending on the tension of the springs 41 and the pressure within the channel 48 and the pressure pipe of the air compressor of the engine. If it is desired to supply the air to the engine at higher pressure the tension of the springs 41 must be varied accordingly by means of the screws 66, so that the fuel is still supplied under the desired pressure.

While the engine and the gear pump are out of operation the valves 36 are closed, sovthat the fuel is not returned from the carburettor to the pump, where it would leak through the spaces between the gear wheels and the walls of their chambers.

It willthus be understood that in my novel gear pump the required smooth slide fit between the axial end faces of the movable parts can be obtained with normal tolerances as there is no summing up of any .inaccuracies of the axial dimensions of any parts in a series arrangement.

Furthermore, since the pipes are connected to a separate cove the casing is not stressed by mechanical tensions due to the pipe connections sothat the chambers in which the gear wheels are mounted are not deformed* and jamming of the gear wheels in the said chambers is avoided. In this respect the construction shown in the drawings in which the plate I2 is interposed between the body I and the head I3 is particularly eifective, because any stress which might Abe exerted by the head is taken up bythe said plate. This plate also'has the result that the be in the form of a channel which is machined in the head by milling, and which in the pump is closed'by the head having a close iit on the plate I2. If the plate were not provided it would be necessary to provide a.

transverse bore in the head in lieu of the channel 66. A further important advantage of my novel gearpump resides in the fact that nearly of said covering means for connecting a duct all of the surfaces to be machined can :be formed by axially directed bores in-the casing. Thus,

nearly all recesses in the casing, and especiallyl the recesses provided to be in accurately defined mutual relationship can be made with the work piece xed in the same position on the working table of the machine tool. the casing is particularly facilitated by the cylindrical shape ofthe same. liilso, as herein shown, the auxiliary devices of the pump, viz, control valves, back pressure valves, by-pass .valves and so' on can be easily applied in the casing.

I contemplate also that-more than three spur gears may be combined according to the principle herein disclosed. For example, four spur gears may be combined in a common casing and in a common plane, thus forming three pairs of uid-displacing gears and making up together a triple-type pump, or five spur gears may be arranged to form a quadruple-type gear pump, depending on the required output of the pump, as will readily occur to one skilled in the art.

I am awarethat many further changes may be made and numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise than is necessitated by the prior art.4

I claim:

1. In a gear pump, comprising a casing having an integral body formed with cylindrical bores disposed oney beside the other and with their axes parallel and merging one into the other in pairs, cover means for closing said bores at least at one of their ends, meshing gear Wheels within said bores, and driving means for The machining ci? connected with a suction chamber with a duct connected with a. delivery chamber, and in a spring pressed valve for normally closing said channel made in the covering means, the power of said spring being such thatthe valve is opened by pressure being built up within the suction chamber connected with said-channel.

A7. A gear pump, comprising a casing composed of an integral :body formed ywith cylindrical bores disposed one beside the other and with their axes parallel and merging one into the other in pairs, said body having a nished end face, and

covering means for said body one located on said nished end face, meshing gear Wheels within said bores, driving means for said gear wheels, said covering means being formed with suction and delivery passages, and said body being formed with suction anddelivery chambers and bores of circular cross-section located with their axes parallel to the axes of said bores enclosing the gear wheels and connecting said suction. and pressure chambers respectively with said suction and delivery. passages for conveying iluid from said suction passage to the gear wheels and from the gear wheels to said delivery said gear wheels, the improvement which consists in suction and.l delivery passages formed in the said covering means and constructed for having 'suction and pressure pipes connected thereto, and suction and delivery chambers and ducts formed in said body, said suction and de,

livery chambers communicating with said bores and being connected through said ducts respectively with said suction and delivery passages respectively for conveying iiuid from said suction passage to said bores and gear wheels and away therefrom to said pressure passage.

2. In a gear pump as claimed in claim 1, the improvement which consists in said ducts connecting the suction and delivery chambers with the suction and delivery passages being in the form of :bores of circular cross-section made in the said body and disposed with their axes parallel to the axes of the bores receiving the gear wheels.

3. In a gear pump as claimed in claim 1. the improvement which consists inthe said suction and delivery passages being made in the same cover member.

v 4. In a pump as claimed in claim 1, theimprovement which consists in a duct in the pump casing connecting correspond-ing suction and pressure chambers with each other, and in a valve for normallyvclosing said duct.

5. In a pump as claimed in claim 1, the'irnprovement which consists in a duct in the form o1 an axial bore of circular cross-section in said body forconnecting corresponding suction and pressure chambers with each other, and in a valve for normally closing said duct.

6. -In a gear pump as claimed in claim 1, the improvement which consists in a channel in one passage, and said covering means bearing on said finished face being formed with a channel connecting said bores connected respectively with the suction and delivery chambers, and a spring pressed valve for normally closing `said channel. mounted within the bore connected with said suction passage and seated on said finished end face, the spring acting on said valve having a power such that the valve is unseated by pressure within the bore connected with the suction passage.

8.*In a gear pump as claimed in claim 1, the improvement which consists in providing a check valve at the delivery end of the duct connected with the deliverypassagefor closing the bores containing the gear wheels against the delivery passage.

9. A gear pump, comprising a casing composed of an integral body formed with cylindrical bores disposed one beside the other and with their axes parallel and mergingy one into the other in pairs, and covering'means for said body, one oi said 4covering means comprising a head and a plate located between the said head and one o'f the end faces ofthe body, meshing gear wheels within said bores, drivingmeans' for said gear wheels, said head being formed with suction and delivery passages, and said body being formed with suction and delivery chambers communieating with said fbores, and with bores of circular cross-section located with their axes parallel to the axes of said bores enclosing the gear wheels, said plate being formed with bores in alignment with said bores of circular crosssection, said bores of circular cross-section and bores in'said plate connecting said suction and delivery chambers respectively with said-suction and delivery passages in said head for conveying uid i'rom `said suction passage to said gear wheels and from said gear wheels to said delivery passage, bushings located in said bores communicating with said delivery chamber and in said bores made in said plate so as to center said plate relatively to said body, and spring pressed check valves guided in and seated on said bushingsin position for preventing backviiow of thel iluid fromssaid pressure passage controlled piston is disposed within said bore controlling the said controlled connection.

1l. In a gear pump as claimed in claim 1, the improvement which consists in a cylindrical bore in said body disposed with its axis parallel to the axes of said bores containing the gear wheels and communicating with said suction chamber, chambers made in opposite covering means one having a supply of a iluid under pressure and the other communicating with said delivery passage, said cylindrical bore parallel to the bores containing the gear wheels being open with its ends to said chambers in the covering means, and a spring pressed piston within said cylindrical bore held in equilibrium therein by the pressure within said delivery passage, the pressure within said chamber having a supply of a fluid under pressure and by said spring and controlling the connectionbetween the said suction chamber and delivery passage.

l2. A gear pump, comprising a casing composed of an integral body formed with cylindrical bores disposed one beside `the other and with their axes parallel and merging one into the other in pairs, and covering means for said body, meshing gear wheels within said bores, driving means for said gear wheels, said covering means being formed with suction and delivery passages, and said body being formed with suction and delivery chambers communicating with said bores and with said suction and delivery passages for conveying uid from said suction passage through the gear wheels and to the delivery passage, said body being formed with an axial bore communicating at one end with said delivery passage and having an opening in its wall adapted to establish controlled connection with a suction chamber, a spring pressed piston within the last named bore controlling the said connection, and

means for imparting rotary movement to said piston as it moves axially within its bore.

13. In a gear pump as claimed in claim 1, the improvement which consists in a cylindrical bore made in said body and located with its axis parallel to the axes of said bores containing the gear wheels and open at one end to said pressure passage and having an opening in its wall for establishing connection between a suction chamber and the pressure passage, a piston in said bore adapted to establish connection between said pressure passage and suction chamber, a spring acting on said piston for holding the same in equilibrium with the pressure in said delivery passage, and means for varying the tension of said spring.

14. In a gear pump comprising a casing composed of an integral body and heads securedto the opposite ends thereof, three bores made in said body -with'their axes parallel and merging one into the other in pairs, meshing impelling gear wheels within said bores, and driving means for said gear wheels, the improvement herein described which consists in suction and delivery passages made in one of said heads, two suction chambers and two pressurechambersmade in said body and communicating with said bores at the merging portions thereof, four bores made in said body with their axes parallel to the axes of the said bores enclosing the gear wheels and connected respectively with said suction and pressure chambers and said suction and delivery pasages for conveying iluid from the suction side of the pump through said gear wheels and to the pressure side of the pump, channels made in one of said heads in position for connecting in pairs bores connected respectively with said suction and delivery passages, spring pressed valves for normally closing said channels, the power of the 'springs of said valves being such that the valves i are opened by pressure built up at the suction side of the pump, two bores made in said body with their axes parallel to the axes of said gear wheels and open to the pressure side of said pump and having their walls formed with slots adapted to establish communication between the pressure side and the suction side of the pump, and spring pressed pistons within said last named bores controlling said slots.

15. A gear pump as claimed in claim 1, in which a plate is located between the said body and the Icover means having said suction and delivery passages formed therein, and in which one of the said passages is in the form of an open channel made in the said cover means and closed by the said plate.

FRITZ EGERSDRFER. 

